Data commit

Task/Loops-Increment-loop-index-within-loop-body/Haskell/loops-increment-loop-index-within-loop-body-1.hs

@@ -0,0 +1,27 @@
+import Data.List
+import Control.Monad (guard)
+
+isPrime :: Int -> Bool
+isPrime n
+  | n <= 3 = n > 1
+  | n `mod` 2 == 0 || n `mod` 3 == 0 = False
+  | otherwise = l2 5 n
+  where l2 d n = x > n || l3 d n
+          where x = d * d
+                l3 d n
+                  | n `mod` d == 0       = False
+                  | n `mod` (d + 2) == 0 = False
+                  | otherwise = l2 (d + 6) n
+
+showPrime :: Int -> Int -> [(Int, Int)]
+showPrime i n = if isPrime i
+                then (n, i) : showPrime (i+i) (n+1)
+                else showPrime (i+1) n
+
+digitGroup :: Int -> String
+digitGroup = intercalate "," . reverse . map show . unfoldr (\n -> guard (n /= 0) >> pure (n `mod` 1000, n `div` 1000))
+
+display :: (Int, Int) -> String
+display (i, p) = show i ++ " " ++ digitGroup p
+
+main = mapM_ (putStrLn . display) $ take 42 $ showPrime 42 1

Task/Loops-Increment-loop-index-within-loop-body/Haskell/loops-increment-loop-index-within-loop-body-2.hs

@@ -0,0 +1,19 @@
+import Data.Numbers.Primes
+import Data.List (intercalate)
+import Data.List.Split (chunksOf)
+
+series :: Integer -> Integer -> [(Integer, Integer)]
+series = go
+  where
+    go i n
+      | isPrime i = (n, i) : go (i + i) (succ n)
+      | otherwise = go (succ i) n
+
+showPair :: (Integer, Integer) -> String
+showPair (i, n) = show i ++ " -> " ++ showInteger n
+
+showInteger :: Integer -> String
+showInteger = reverse . intercalate "," . chunksOf 3 . reverse . show
+
+main :: IO ()
+main = mapM_ (putStrLn . showPair) (take 42 $ series 42 1)